Process for producing an electromagnetic subassembly for a magnetic levitation railway

ABSTRACT

The invention relates to a method of manufacturing an electromagnetic assembly in the form of a magnet pole or of a stator packet of a long stator linear motor for a magnetic levitation train. The assembly includes a sheet stack ( 8 ) consisting of ferromagnetic material, and at least one further component ( 12, 13, 14 ). According to the invention, the sheet stack ( 8 ) is assembled from raw magnetic steel sheets and is positioned in a shaping tool. Thereafter by introduction of a hardenable mixture into the tool and hardening or hardening out of the said mixture, the sheets are in a single working step surrounded with the mixture and connected together to form the finished sheet stack ( 8 ). In the same working step, the sheet stack ( 8 ) is connected to the component ( 12, 13, 14 ) and the assembly as a whole is provided with its final electrical, magnetic, mechanical and/or geometric properties.

[0001] The invention relates to a method according to the preamble toclaim 1 and an assembly produced according to this method in the form ofa magnet pole or stator packet for long stator linear motors of magneticlevitation trains.

[0002] In a known method of this type (DE 31 10 339 C2) formanufacturing stator packets, firstly strips made from silicatedmagnetic steel sheets are provided preferably on both sides withadditional adhesive layers, which consist for example of a pre-hardenedduroplastic adhesive and if necessary are already applied in the rollingmill in a complex, expensive working step. The manufacture of sheetstacks is then carried out in that sheet blanks or lamellae are stampedout from such sheet strips drawn off from coils (drums), and these arethen combined into stacks and thereafter, by heating and simultaneouspressure, are mechanically securely connected together to form a sheetstack. Then the finished sheet stacks are additionally provided with acoating of an epoxy resin or the like, in order to provide the cut edgesof the plates revealed during stamping with an additional anti-corrosionlayer. Finally the individual sheet stacks are connected by gluing,screwing, clamping or the like to other components, in particular tocrosspieces intended for their attachment on a travel path, forming thefinished stator packet; in order to obtain sufficient mechanicalstability as a rule disadvantages from the electromagnetic stand pointmust be accepted, e.g. with respect to the electromagneticallyunfavourable cross-sectional shapes of the groove which are howeverdesirable for attachment of the electrical conductors.

[0003] Magnet poles for long stator linear motors are produced in asimilar way, finished sheet stacks then being provided with windings andpole jaws or the like, and connected. In this case also compromises mustbe accepted between mechanical stability and electromagnetic properties,e.g. with respect to the geometry of the iron core made out of the sheetstack, which is necessary for reliable assembly of the windings, and yetentails undesirable magnetic dispersion effects.

[0004] Due to the installations required for coating the strips ofmagnetic steel sheet, methods of this type involve high investmentcosts. A further disadvantage is that the waste occurring duringstamping is provided with an adhesive layer, which ought to be avoidedfor reasons of environmental protection, and which preventsproperly-classified recycling of the sheet steel waste. Finally, theknown method requires numerous successive partial steps, whichrespectively serve a pre-selected partial purpose.

[0005] The object underlying the invention is therefore to alter theabove described method for manufacturing magnet poles and stator packetsin such a way that lower investment costs and fewer individual steps arerequired and better adaptation is possible to the functions of thevarious components involved. Moreover, high mechanical strength and highresistance to external weathering influences are to be achieved.

[0006] The characterising features of claims 1 and 15 serve to achievethis purpose.

[0007] Further advantageous features of the invention will becomeapparent from the secondary claims.

[0008] The invention will be explained in more detail in the followingwith reference to two embodiments given by way of example, which areshown in the accompanying drawing on slightly differing scales. Shownare:

[0009]FIG. 1: a perspective, exploded view of some plates of a sheetstack for a magnet core according to the invention;

[0010]FIG. 2: a perspective view of the components used to produce acomplete magnet core, with the sheet stack in the stacked condition;

[0011]FIG. 3: a perspective view of the magnet core according to FIG. 2in the combined condition of all the components;

[0012]FIG. 4: a perspective view of the winding of a winding member ofthe magnet core according to FIG. 3;

[0013]FIG. 5: a perspective view of a magnet pole produced with themagnet core according to FIGS. 1 to 4, having a winding for a lineargenerator, after arrangement in one half of a tool, serving toimpregnate the sheet stack, for wetting through the sheet stack and thewinding, for connecting the sheet stack with the other components andfor surrounding the entire magnet pole with a hardenable mixture;

[0014]FIG. 6: a cross-section through the tool along the line VI-VI ofFIG. 5 with the magnet pole inserted;

[0015]FIG. 7: a schematic view of the insertion of a hardenable mixtureinto the tool according to FIGS. 5 and 6;

[0016]FIG. 8: a perspective view of the completed magnet pole;

[0017]FIG. 9: a view corresponding to FIG. 1 of some sheets of thestator sheet stack according to the invention;

[0018]FIGS. 10 and 11: the stator sheet stack according to FIG. 9 in thestacked condition before or after application of a number ofcrosspieces;

[0019]FIG. 12: a perspective view of a stator packet formed from thestator sheet stack and the crosspieces according to FIGS. 10 and 11,after arrangement in one half of a tool, serving to impregnate the sheetstack, for wetting through the sheet stack and the crosspieces, forconnecting the sheet stack to the crosspieces and for surrounding theentire stator packet with a hardenable mixture;

[0020]FIG. 13: a cross-section through the mould along the lineXIII-XIII of FIG. 12;

[0021]FIG. 14: a schematic view according to FIG. 7 of the insertion ofthe hardenable mix into the tool according to FIGS. 12 and 13;

[0022]FIG. 15: the finished stator packet and

[0023]FIG. 16: on a greatly enlarged scale, a cross-section through anindividual groove of the stator packet according to FIG. 15.

[0024] The invention will be explained in more detail in the followingwith reference to the examples of a magnet pole and of a stator packetfor a magnetic levitation train with a long stator linear motor, whosestructure, function and geometry are well known to the person skilled inthe art. For reasons of simplicity in this respect, reference is madefor example to DE 31 10 339 C2, DE 33 03 961 C2, DE 34 10 119 A1 and DE39 28 277 C1, and the contents of these documents are thus, as far asnecessary, made the subject-matter of the present disclosure.

[0025] In a known way, a magnet pole includes an iron core consisting ofa sheet stack, and a winding applied thereto. According to FIGS. 1 to 8the iron core consists of a plurality of individual sheets or lamellae1, arranged in parallel and aligned flush on one another, which havebeen obtained for example by stamping out from a ferromagnetic magneticsheet strip, which has been unwound from a drum (coil), and passed to astamping tool. According to the invention, a raw magnetic steel sheetstrip is involved. In this respect the term “raw” is understood to meanthat the magnetic steel sheet strip, contrary for example to DE 31 10339 C2, has no adhesive layer applied in a separate working procedure.On the contrary, the sheet strip, as is conventional with magnetic steelsheets, can be provided with an electrically insulating layer by meansof a lacquer coating an oxide layer or other means which may be appliedin a cost-effective manner on both sides. This layer can already beapplied in the rolling mill to the sheet strip, and in the case ofmagnetic steel sheets conventional today usually consists of anextremely thin silica phosphate layer, which is produced as the magneticsteel sheets are rolled out. For the purposes of the invention thislayer is comparatively irrelevant, as under certain circumstances it canalso be totally omitted.

[0026] The individual sheets 1, of which only a few are shown in FIG. 1,in the embodiment have a thickness of for example 0.35 to 1.00 mm, andhave identical dimensions, and each have a forward or rear wide side 2,and in the respective circumferential directions, a narrow upper side 3,a lower side 4 and two side edges 5 and 6. In addition, they are eachprovided during the stamping procedure at identical points with at leastone hole 7 and in order to form the iron core after the stampingprocedure into packets 8 (FIG. 2), are stacked, being laid on oneanother with their forward or rear wide sides 2 flush and parallel withone another. The number of sheets 1 per packet 8 depends on the size andthickness of the magnetic pole to be produced. The mutual alignment ofthe sheets 1 is carried out appropriately with the aid of slide blocksor rods 9, upon which the sheets 1 are threaded with their holes 7. Inthe stacked sheet packet 8, the upper sides 3 of the individual sheets 1form a magnet pole surface 10, while the undersides 4 form an assemblysurface 11.

[0027] After formation of the stack, the two end faces of the sheetstack 8 are respectively connected to pole jaws 12,13, which ensure thenecessary stability of the magnetic core and serve as carriers for awinding body 14 (FIGS. 2 and 3). The relative alignment of the pole jaws12,13 to the sheet stack 8 is appropriately carried out in that the polejaws 12,13 are provided with holes 15, and are thrust with these on theends of the rods 9 projecting out of the sheet stack 8, and thenaccommodate these ends in themselves. Although the pole jaws can alsoconsist of iron, they are preferably made from aluminium in order toreduce weight.

[0028] The winding body 14 substantially consists of a frame made frominsulating material, e.g. plastic, which in the embodiment surrounds asubstantially cuboid cavity 16, whose dimensions of height, length andwidth substantially correspond to the external dimensions of the sheetstack 8 inclusive of the pole jaws 12 and 13. Moreover the winding body14 is provided on its upper and lower end with a respective outwardlyprojecting surrounding assembly flange 17, so that a surroundingaccommodation space 18 results for a winding 19 (FIG. 4) between the twoassembly flanges 17.

[0029] For correct positioning of the winding body 14 relative to thesheet stack 8, the pole jaws 12,13 are provided on their outer end faceswith guide grooves 20, which are disposed vertically to the rods 9 andto the magnet pole surface 10. Correspondingly, the winding body 14 hason two opposite sides inwardly projecting guide ribs 21, which, when thewinding body 14 is set on the sheet stack 8 from above or below, enterthe guide grooves 20 and then enable a displacement of the winding body14 relative to the magnet pole surface 10 into a desired position (FIG.3), which is appropriately established by a stop means not shown infurther detail.

[0030] As is in particular seen from FIG. 4, the winding body 14, afterits positioning on the sheet stack 8, is provided with the winding 19,which is formed from alternatively succeeding layers of a conductor 23and of an insulator 24, and comes to lie between the assembly flanges17. The conductor 23 consists for example of an endless aluminium stripunwound from a supply coil 25, while the insulator 24 for example is astrip of a conventional insulating film unwound from a supply coil 26.Unwinding of the conductor 23 and of the insulator 24 from the supplycoils 25,26, or their winding onto the winding body 14, is effected in aknown way in the direction of the arrows entered in FIG. 4. Naturally itwould also be alternatively possible to apply the winding 22 onto thewinding body 14 before the latter is mounted on the sheet stack 8, orthe winding, here shown as a layer winding, can be subdivided into aplurality of panels to be connected together.

[0031] In the assembly described in FIGS. 1 to 3 of a magnet core, theindividual plates 1 loosely threaded onto the rods 9, are held inposition only by the rods 9 and the winding body 14, the winding body 14abutting on the lateral edges 5,6 of the sheets 1 and on the forward orrear sides of the pole jaws 12,13. In contrast, the winding 19 is heldin position on the magnet core by the assembly flange 17. Thus thesheets 1 are simultaneously pressed against one another via the polejaws 12,13 with a pre-selected pressure, so that they abut closely onone another. In order to connect all these parts securely, the assemblysubstantially visible from FIG. 4 is inserted into a mould or a shapingtool 28 (FIGS. 5 to 7); in the embodiment what is involved is a tool 28with two tool halves 29 and 30, which are provided similarly to aninjection moulding tool on opposite sides with apertures 31,32, which inthe closed condition of the tool 28 (FIG. 7) form a cavity or hollowmould space, whose dimensions are only slightly larger than the outerdimensions of the finished wound magnet pole.

[0032] For correct positioning of the magnet pole in the cavity, thereserve on the one hand for example the lower assembly flanges 17, and onthe other hand if required additional positioning means 33. In theembodiment these consist of rods, which project into holes 34 (FIG. 2),which are formed in the pole jaws 12,13 additionally to the holes 16 andat points which remain accessible beneath the winding body 14 in theassembled condition, as in particular FIG. 6 shows. The positioningmeans 33 are for example mounted in the side jaws of the tool half 30and upon closing of the tool 28 are moved automatically into the holes34. Further positioning means not shown may be disposed in the base ofthe tool half 30. In this way it is possible to align the sheet stack 8and the winding body 14 relative to one another in the tool.

[0033] One of the tool halves 29,30 is provided according to FIG. 7 withan inlet opening extending as far as the cavity, to which is connectedthe outlet of a line 37 provided with a control valve 6, and which inaddition has two inlets 40 and 41 each connected to a metering pump 38and 39. Preceding the metering pumps 38,39 in each case is a respectivemixing container 42,43 and following them is a mixer 44 incorporated inthe line 37. These devices serve the purpose of preparing a hardenablemixture, in particular a casting resin mixture, and after closing thetool 28, of introducing it into the cavity. In this way, in one singleworking step, a plurality of objects are achieved. On the one hand theloosely stacked sheets 1 of the sheet stack 8, by means of insertion ofthe mixture, are provided with the adhesive layers necessary betweenthem, and simultaneously with the use of an adhesive, they are connectedtogether to form a solid packet. On the other hand this packet isconnected with the assembly 45 forming with the other components thefinished magnet pole (FIG. 8), to form a solid constructive unit, whichsimultaneously is covered as an entire unit and in particular at the cutedge of the sheets 1, with an anti-corrosion layer, which is indicatedschematically in FIG. 6 by a line 46. The pre-selectable thickness ofthis layer substantially depends on the spacing between the variouscomponents of the assembly after insertion into the tool from oneanother, and from the wall portions defining the cavity, and can forexample come to up to 10 mm, preferably 2 to 3 mm. Moreover, theassembly 45, due to the complete coverage with the hardenable mixture,receives its final mechanical electromagnetic and geometric properties,the special design of the tool 28 depending on the individual case, andthe apertures 31,32 forming the mould hollow, contributing to this.

[0034] The mixture to be used is preferably a hardenable (durpolastic)casting resin mix on a basis of epoxy or polycyloolefine and consistsfor example of two components, namely for example a casting resinprepared in the mixing container 42 and if necessary provided with anadditive, e.g. an epoxy resin or an epoxy resin mixture, and a hardenerprepared in the mixing container 43, e.g. an epoxy hardener. The twocomponents are metered in a pre-selected ratio by means of the meteringpumps 38,39, introduced into the mixer 44, intimately mixed togethertherein and then from that point introduced via the line 37 and thecontrol valve 36 into the cavity. Thus supply of the casting resinmixture is effected at a pressure of e.g. 1-3 bar, in order inparticular to wet through or impregnate the sheet stack 8 in such a waythat all the plates are covered on all sides by a thin casting resinlayer.

[0035] After the cavity is filled, the casting resin mixture, preferablywith heating of the entire tool 28, is left to harden, until removalfrom the mould can take place and the finished assembly 45 can beremoved from the tool 28. Alternatively, the tool 28 may also be heatedbefore introduction of the casting resin mass. Moreover, it is best onlyto harden the casting resin mass in the tool 28 and then to subject thefinished assemblies 45 to a heat treatment, in order for example toterminate the hardening procedure and/or to expel slowly-evaporatingcomponents. In addition, a cleaning stage could be added.

[0036] In an embodiment of the invention felt to be best until now, thecasting resin mixture is introduced after the pressure-gelatingprocedure into the cavities between the plates 1 and the othercomponents of the assembly 45, or between these and the walls of themould hollow. The pressure-gelating process is particularlyadvantageous, as the shrinkage occurring during hardening is compensatedfor in this way. In this method, which is also termed a reaction resininjection moulding (e.g. Kunststoff-Lexikon, Hrg. Dr.-Ing. K. Stoeckhartand Prof. Dr.-Ing. W. Woebcken, Carl Hanser Verlag, München, BRD, 8thedition, 1992), both reaction resin masses with a long pot time and alsohighly-reactive resin masses can be used, which are automatically mixedand metered with the aid of the mix container 42,43 only briefly beforeinjection into the tool 28, in an automatic manner. Thus the two inlets40,41 shown in FIG. 7 can also open into a pressure container, fromwhich the prepared reaction resin mixture is then expressed into theline 37 by means of compressed air.

[0037] Numerous mixtures, particularly those which are thermallyhardenable, are suitable for producing the assembly 45.

[0038] Preferred hardenable mixtures are epoxy resin/hardener mixturesand mixtures of a tensioned cycloolefine and a catalyst for thering-opening metathesis polymerisation.

[0039] Suitable as epoxy resins, which can be used according to theinvention are all types of epoxy resins, such for example as those whichcontain groups of the formula

[0040] directly bonded to oxygen, nitrogen or sulphur atoms, in whicheither R′ and R″ each contain one hydrogen atom, in which case R″ meansa hydrogen atom or a methyl group, or R′ and R″ together represent—CH₂CH₂ of —CH₂CH₂CH₂—, in which case R″ means a hydrogen atom.

[0041] As examples of such resins there should be mentionedpolyglycidylesters and poly(β-methylglycidyl)esters, which can beobtained by conversion of a compound containing two or more carboxylicacid groups per molecule with epichloryhdrin, glycerine dichlorhydrin orβ-methylepichloryhydrin in the presence of alkali. Such polyglycidylesters can be derived from aliphatic polycarboxylic acids, e.g. oxalicacid, succinic acid, glutaric acid, adipic acid, pimelic acid, subericacid, azelaic acid, sebacic acid or dimerised or trimerised linolaicacid, from a cycloaliphatic polycarboxylic acids such astetrahydrophthalic acid, 4-methyltetrahydrophthalic acid,hexahydrophthalic acid and 4-methylhexahydrophthalic acid, and fromaromatic polycarboxylic acids, such as phthalic acid, isophthalic acidand terephthalic acid.

[0042] Further examples are polyglycidyl ethers and poly(β-methylglycidyl) ethers, which are obtainable by conversion of acompound containing at least two free alcoholic and/or phenolic hydroxylgroups per molecule with the corresponding epichlorhydrin under alkalineconditions, or also in the presence of an acidic catalyst withsubsequent alkali treatment.

[0043] These ethers can be produced with poly-(epichlorhydrin) fromacyclic alcohols, such as ethylene glycol, diethylene glycol and higherpoly-(oxyethylene)-glycols, propane-1,2-diol undpoly-(oxypropylene)-glycols, propane-1,3-diol, butane-1,4-diol,poly-(oxytetramethylene)-glycols, pentane-1,5-diol, hexane-1,6-diol,hexane-2,4,6-triol, glycerine, 1,1,1-trimethylolpropane, pentaerythriteund sorbite, from cycloaliphatic alcohols, such as resorcite, chinite,bis-(4-hydroxycyclohexyl)-methane, 2,2-bis-(4-hydroxycyclohexyl)propaneand 1,1-bis-(hydroxymethyl)-cyclohexene-3, and from alcohols witharomatic cores, such as N,N-bis-(2-hydroxyethyl)-aniline andp,p′-bis-(2-hydroxyethylamino)-diphenylmethane. They can also beproduced from single-core phenols, such as resorcin und hydroquinone,and multicore phenols such as bis-(4-hydroxyphenyl)-methane,4,4dihydroxydiphenyl, bis-(4hydroxyphenyl)-sulfone,1,1,2,2-tetrakis-(4hydroxyphenyl)ethane, 2,2-bis-(4-hydroxyphenyl)propane (bisphenol A) and 2,2-bis-(3,5-dibromo-4hydroxyphenyl)-propane.

[0044] Further suitable hydroxy compounds for producing polyglycidylethers and poly(3-methylglycidyl) ethers, are the novolacks obtainableby condensation of aldeyhdes, such as formaldehyde, acetaldehyde,chloral and furfural and phenoline, such for example as phenol,o-cresol, m-cresol, p-cresol, 3,5-dimethylphenol, 4-chlorphenol and4-tert.-butylphenol.

[0045] Poly-(N-glycidyl)-compounds can be obtained for example bydehydrochlorination of the conversion products of epichloryhdrin with atleast two amines containing amino hydrogen atoms, such as such asaniline, n-butylamine, bis-(4-aminophenyl methane, andbis-(4-methylaminophenyl)-methane. Further suitablepoly-(n-glycidyl)compounds are triglycidylisocyanurate andn,n′-diglycidyl derivates of cyclic alkylene ureas, such asethylene-urea and 1,3-propylene-urea, and hydantoines, such for exampleas 5,5-dimethylhydantoine.

[0046] Poly-(S-glycidyl)-compounds are for example the Di-S-glycidylderivates of dithiolene, such as ethane-1,2-dithiol andBis-(4-mercaptomethylphenyl)-ether.

[0047] Examples for epoxy resins with groups of the formula

[0048] wherein R′ and R″ together mean a —CH₂CH₂— or a—CH2-CH2-CH2-CH2-group, are bis-(2,3-epoxycyclopentyl)-ether,2,3-epoxycyclopentylglycidylether,1,2-bis-(2,3-epoxycyclopentyloxy)-ethane and 3′,4′-epoxycyclohexylrnethyl-3′,4′-epoxycyclohexanecarboxylate.

[0049] Also considered are epoxy resins, in which the glycidyl groups orβ-methylglycidyl groups are bonded to heteroatoms of various types, e.g.the N,N,O-triglycidyl derivate of 4-aminophenol, theglycidylether/glycidylester of salicylic acid or p-hydroxybenzoic acid,N-glycidyl-N′-(2-glycidyloxypropyl)-5,5dimethylhydantoine and2-glycidyloxy-1,3-bis-(5,5-dimethyl-1-glycidylhydantoinyl-3)-propane.

[0050] If required, epoxy resin mixtures can be used.

[0051] Preferably, diglycidylethers of bisphenols are used. Examples ofthis are bisphenol A-diglycidyl ether, bisphenol F-diglycidyl ether andbisphenol S-diglycidyl ether. Bisphenol A-diglycidyl ether isparticularly preferred.

[0052] Quite particularly preferred are liquid and low-viscosity epoxyresins. Appropriately the viscosity at 25° C. does not exceed a value of20'000 mPas.

[0053] In a method according to the invention, all the known epoxy resinhardeners can in theory be used.

[0054] Preferably a carboxylic acid or a carboxylic acid anhydride isused as an epoxy hardener.

[0055] aliphatic dicarboxylic acids, such as oxalic acid, malic acid,succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid,azelaic acid, sebacic acid, 3,6,9-trioxaundecandic acid, or dimerised ortrimerised linoleic acid; cycloaliphatic polycarboxylic acids, such forexample as tetrahydrophthalic acid, 4-methyltetrahydrophthalic acid,hexahydrophthalic acid and 4-methylhexahydrophthalic acid; aromaticdicarboxylic acids, such as phthalic acid, isophthalic acid,terephthalic acid or naphthalic acid; or diester-dicarbooxylic acids,which are obtainable for example by conversion of glycols, e.g.polypropylene glycol with two equivalents dicarboxylic acid anhydride,such e.g. as tetrahydrophthalic acid anhydride.

[0056] There can be considered in theory as anhydride hardeners allanhydrides of di- and higher-functional carboxylic acids, such as linearaliphatic polymeric anhydrides and cyclic carboxylic acid anhydrides.

[0057] polysebacic acid polyanhydride, polyazelaic acid polyanhydride,succinic acid anhydride, citraconic acid anhydride, itaconic acidanhydride, alkenyl-substituted succinic acid anhydride,dodecenylsuccinic acid anhydride, maleic acid anhydride, tricarballylicacid anhydride, nadican hydride, methylnadican hydride, linoleic acidadduct on maleic acid anhydride, alkylised endoalkylenetetrahydrophthalic acid anhydride, methyltetrahydrophthalic acidanhydride, tetrahydrophthalic acid anhydride, hexahydrophthalic acidanhydride, pyromellitic acid dianhydride, trimellitic acid anhydride,phthalic acid anhydride, tetrachlorophthalic acid anhydride,tetrabromophthalic acid anhydride, dichloromaleic acid anhydride,chloronadic anhydride and chlorenedicanhydride.

[0058] Preferably liquid or easily-melting dicarboxylic acid anhydridesare used as epoxy resin hardeners.

[0059] Particularly preferred anhydride hardeners aremethylnadicanhydride, tetrahydrophthalic acid anhydride andmethyltetrahydrophthalic acid anhydride, methylnadicanhydride andmethyltetrahydrophthalic acid anhydride being preferably used as anisomer mixture.

[0060] If required the anhydride hardener can be used in combinationwith a reaction accelerator conventional for anhydride hardeners. Thereare suitable for example as reaction accelerators tertiary amines,carboxylic acid salts, metal chelates or organophosphenes. Preferredaccelerators are the tertiary amines, such for example asN,N-dimethylbenzalamine, or substituted imidazoles.

[0061] In a further preferred embodiment of the invention, there is usedas a hardenable mixture a mixture of a tensioned cycloolefine and acatalyst for the ring-opening metathesis polymerisation.

[0062] Within the framework of the present invention, by cycloolefinesis to be understood all cycloolefines with the exception of cyclohexineand its derivates, which cannot be polymerised with the ring-openingmetathesis. Suitable cycloolifines for example are described in WO96/16100 and WO 96/202235.

[0063] Preferably, a Diels-Alder adduct of cyclopentadiene is used inthe method according to the invention.

[0064] Particularly preferred are tetracyclododecine,methyltetracyclododecene and in particular dicyclopentadiene.

[0065] A large number of compounds of the transition metals titanium,vanadium, molybdenum, tungsten, rhenium, iridium, ruthenium and osmiumis known to the person skilled in the art as catalysts for thering-opening metathesis polymerisation (ROMP-catalysts). In this casefor example what is involved are complex metal halogenides,metallo-carbenes or co-ordination catalysts of the Ziegler-Natta type.All these known ROMP-catalysts can in theory be used as component (b) inthe compositions according to the invention.

[0066] A ruthenium (+II)-complex salt or an osmium(+II)-complex salt ispreferably used, particularly preferably a ruthenium (+Il)-complex salt,as component (b).

[0067] As the use of absolutely water-free substances and apparatusrequires an additional outlay, it is recommended thatmoisture-insensitive ROMP-catalysts be used, such for example as theruthenium (+II) and osmium (+II) complex salts described in WO 96/16100and WO 96/20235.

[0068] Particularly preferred ROMP-catalysts are

[0069] Particularly preferred ROMP-catalysts are

[0070] [(Cyclohexyl)₃P]₂RuCl₂, [(C₆H₅)₃P]₃ RuCl₂, [(C₆H₅)₃P]₃ (CO) RuH₂,

[0071] [(C₆H₅)₃P]₃ RuCl (cyclopentadienyl),

[0072] [(Cyclohexyl)₃P]₂(CH₃OH)Ru(tosylate)₂, [(o-tolyl)₃P]₃RuCl₂,

[0073] [(CH₃)₂CH]₃ P(p-cymol)RuCl₂ and in particular

[0074] (Cyclohexyl)₃P(p-cymol)RuCl₂.

[0075] The desired viscosity of the hardenable mixture can be adjustedby the addition of thermoplastic materials. Examples of suitablethermoplastics are polystyrol, polynorbornene (e.g. Norsorex NS of theCompany Nippon Zeon), hydrated polynorbornene derivates (e.g. Zeonox ofthe Company Nippon Zeon) polycylooctene, (e.g. Vesternamer of theCompany Huls) and polybutadiene.

[0076] A particular advantage of the method described for manufacturingthe assembly 45 resides in the fact that the process steps ofimpregnation of the loosely layered sheet stack 8, surrounding of theother components and of the entire assembly 45 with an anti-corrosionlayer 46 (FIG. 6) and the secure connection of all parts together can beeffected in one single working step, without the necessity foradditional mechanical connecting means. Thus the procedures of loadingand unloading the tool 28, opening and closing the tool 28 and fillingof the remaining cavities within the hollow mould may be to a largeextent automated.

[0077] If in addition hardenable mixtures with electrically insulatingproperties are used, which applies to the abovenamed materials, thenthere results the further advantage that the sheets 1 are surrounded inthe single named working step with an electrically insulating layer, sothat in theory also entirely untreated magnetic steel sheets having noinsulating layers, can be used as initial materials.

[0078] A further outstanding advantage of the invention in this caseresides in the fact that the individual sheets 1 of the sheet stack 8can be inserted in an in fact totally untreated but however stacked anddensely packed condition into the tool 28. Due to the natural surfaceroughness in the area of their wide sides 7, there remain between thesheets 1, even in the stacked, densely packed condition a sufficientlylarge number and size of cavities, which fill with this mixture upon itspenetration into the tool 28, which then, in the hardened condition,provides the necessary insulation between the individual sheets 1without the formation of disruptive bubbles of the like. This effect canbe further improved and optimised in that, before or during injection ofthe mixture, the cavity is at least partly evacuated, in order toproduce a slight reduction in pressure of e.g. 2 to 10 millibars, ifnecessary to be determined by tests, and thus to suction the mixtureadditionally into the cavity, so that simultaneously the necessity isremoved of expelling the air still located in the cavity with the aid ofthe mixture.

[0079] Finally a further advantage is that the external shape of theassembly 45 can be selected substantially independently of the shape ofthe individual sheets 1 produced by stamping, and of the winding 19 laidaround it. In particular, by means of corresponding formation of themould hollow, it can be assured that the external anti-corrosion layeris sufficiently thick and environmentally resistant, whilstsimultaneously by means of the stacking of the sheets 1 and the pressureused to clamp them, the required thin adhesive and if necessaryinsulating layers can be produced between the individual sheets 1.

[0080] The embodiment according to FIGS. 1 to 8 may be modified and/orsupplemented in many ways. If for example the assemblies 45 serve thepurpose of producing a heteropolar inductor for the magnetic levitationvehicle (DE 34 10 119 A1), then, in order to reduce weight, theindividual sheets 1 can be provided in a central lower area with arespective aperture 47 (FIG. 1), as this section is not required formagnetic purposes. During the casting procedure, a core 48 (FIG. 6) canbe laid into the groove thus resulting in the stacked sheet stack 8, sothat the groove is not filled with mixture and yet the walls defining itare provided with a thin anti-corrosion layer. It is further possible toprovide the sheets 1 at their upper sides 3 during stamping withapertures 49 (FIG. 1) which in the stacked condition form grooves 50(FIG. 2), which abut on the magnet pole surface 10 and can be insertedinto the additional windings 51 according to FIGS. 5 and 6, which form alinear generator known per se during operation of the magneticlevitation vehicle. These windings 51 also form a constructive elementwhich is securely connected to the remaining assembly 45 by means of thepenetration of the casting compound, and if necessary is provided withan additional protective layer.

[0081] Finally, the undersides 4 (FIG. 1) of the sheets 1 of the entiresheet stack and/or the undersides of the pole jaws 12,13 can be keptfree of mixture. For this purpose for example the cavity of the tool 28is so designed that the said undersides, after location of the variouscomponents in the tool 28, abut directly on corresponding wall portions.As the undersides of the sheet stacks and/or of the pole jaws 12,13 in acomplete magnet, usually consisting of a plurality of such magnet poles,are magnetically connected together by means of ferromagnetic pole backslocated beneath the windings 19, it is ensured in this way that in theboundary surfaces between the magnet poles and the magnet back nomagnetically disruptive slots formed by included mixture arise.

[0082] FIGS. 9 to 15 illustrate the manufacture of a stator packet forthe long stator linear motor of a magnetic levitation vehicle. Similarlyto FIGS. 1 to 8, the stator packet contains a plurality of sheets orlamellae 61, of which only a few are shown in FIG. 9 and which areobtained by stamping from a raw ferromagnetic sheet metal stripcomprising no adhesive layer. In the embodiment, the sheets 61 haveidentical dimensions and each have a forward and rear wide side 62 andrespectively in the circumferential direction a narrow upper side 63,underside 64 and two side edges 65 and 66. By means of auxiliary meansnot shown in further detail, the sheets 61 are stacked into sheet stacks67 (FIG. 10), being applied against one another with their forward orrear wide side 62, and being aligned flush with one another. The numberof sheets 61 used in this case depends on the required electrical andmagnetic properties for the long stator linear motor.

[0083] During the manufacture by stamping, the sheets 61 are provided ontheir upper sides 63 with apertures 68 and on their undersides 64 withapertures 69. After stacking of the sheets 61 to form the sheet stack 67(FIG. 10), the apertures 68 respectively form grooves 71 and theapertures 69 respective grooves 72. The apertures 68 open towards theupper side 63, and grooves 70, have for example a dovetail cross-sectionand serve to receive correspondingly shaped foot sections 73, which areintegrally formed on straight crosspieces 74 substantially in a double-Tshape in cross-section. In contrast, the apertures 69 open towards theundersides 64 and grooves 72, have substantially rectangular or squarecross-sections. After formation of the stack, the foot sections 73 ofthe crosspieces 74 are inserted in the direction of the arrows shown inFIG. 10 into the grooves 71 of the sheet stack 67, and are centredtherein, so that the loosely initially-mounted assembly visible in FIG.11 results. Alternatively, the sheets 61 may of course also beindividually threaded onto the correspondingly positioned crosspieces74.

[0084] The finally mounted assembly, similar to the assemblies accordingto FIG. 4, is now inserted into a tool 75, (FIGS. 12 to 14) which in theembodiment has two tool halves 76,77, which are provided at oppositesides with apertures 78,79, which in the closed condition of the tool 75form a mould hollow or cavity, whose dimensions are slightly larger thanthe external dimensions of the inserted assembly.

[0085] The crosspieces 74 are provided at their ends which projectslightly beyond the sheet stack 67, with bores 80 intended toaccommodate attachment screws. In order that these remain free duringfilling of the cavity with hardenable mixture, the tools 76,77, at thepoints where the bores 80 come into contact, are provided with holes 81,into which locking pistons 82 may be introduced. These are secured atthe end of the piston rods 83 of a respective pneumatic or hydrauliccylinder 84 attached to the associated tool half 76,77, and which isshown in the left-hand part of FIG. 13 in the retracted condition, andin the right-hand part of FIG. 13 in the extended condition. In theextended condition the locking bolt 82 for example is applied againstthe underside of the crosspiece 74 and against a lateral sectionsurrounding the associated bore 80, so that one end of the bore 80 isclosed. Simultaneously, the locking piston 82 presses the crosspiece 74securely against the opposed wall section of the associated tool half,which in this way closes the other end of the bore 80, so that nomixture can penetrate. If required, a closure stopper 85 passing intothe bore 80, can be applied to the locking pistons 82 and/or the opposedwall.

[0086] The pistons 82 in addition bring about positioning of thecrosspieces 74 relative to the tool 75. If required additionalpositioning means not shown in further detail, can be provided forexample on the base of the tool 75, and which position the sheet stack67 relative to the tool 75 and relative to the crosspieces 74. Finally,if necessary, means corresponding to the cylinder 84 or other means canbe provided, which act for example through side walls of the tool 75 onthe sheet stack 67, in order to press its sheets 61 closely against oneanother.

[0087] After the tool 75 is closed in the direction of the arrow shownin FIG. 13, and after extension of the piston rods 83 into the positionshown in the right-hand part of FIG. 13, a mixture is introduced intothe cavity, for which purpose the tool 75, similarly to FIG. 7, isprovided with an inlet opening extending as far as the cavity, and whichis connected by means of a line 86 (FIG. 4) to a control valve 87 andvia metering pumps 88,89 to mixing containers 90,91, which contain areaction resin or a hardener or the like, in order to prepare themixture therefrom. The reaction resin and hardener components aremetered with the metering pumps 88,89 are mixed in a mixer 92. Theprocess steps of introduction of the mixture into the cavity, ofhardening or hardening out of the mixture, of heating and if necessaryof cleaning, are similar to the embodiment according to FIGS. 1 to 8 andtherefore need not be described again. The same applies to the mixturesto be used, particularly casting resin mixture, whose preparation, thepreferred injection of the mixture at a pressure of e.g. 1 to 3 bar, thepreferable additional evacuation of the cavity and the preferredapplication of the pressure-gelling method.

[0088] After removal from the mould, the finished assembly 93 visible inFIG. 15 is obtained in the form of a stator packet.

[0089] As with the manufacture of the assembly 45, there results in theembodiment according to FIGS. 9 to 15 the advantage that theimpregnation of the loosely layered sheet stack 67 consisting of notparticularly pre-treated sheets 61, the surrounding of the remainingcomponents and of the entire stator packet with an anti-corrosion layer,and the secure connection of all parts together can be effected in onesingle process step, and the procedures necessary therefore can to alarge extent be automated. Finally also, the external shape of thefinished assembly 93 can be selected largely independently of thestamped shape of the individual sheets 61, as will be explained withreference to some possible variants.

[0090] The assembly 93 is secured in a known way (DE 39 28 277 C1) withthe aid of the bore 80 and attachment screws introduced therein toconnecting members of the track support of a magnetic levitation track.Thus surface sections 94, shown cross-hatched in FIG. 15, located on theupper side of the crosspieces 74, and surrounding the ends of the bores,serve as stop or reference surfaces which establish the precise positionof the crosspieces 74 and thus of the entire assembly 93 relative to thetrack support. These surface sections 94 are preferably not covered byan insulating or anti-corrosion layer, in order to avoid inaccuracies inpositioning, rotation or settling of this layer during tightening of theattachment screws and if necessary loosening of the attachment screwscaused thereby during later operation of the magnetic levitation track.For this purpose, the locking pistons 82 press the surface sections 94cross-hatched in FIG. 15 in such a way against a correspondingly formedwall of the tool 75, that no mixture can settle there, while at theother point of the overall assembly 93 a small intermediate space 95(FIG. 13) always remains between it and the walls of the tool 75, whichenables the formation of an external layer of the mixture, particularlyserving as an anti-corrosion means. This is most simply achieved bycorresponding steps 96 in the walls forming the cavity.

[0091] The lower grooves 72 of the sheet stack 67 serve in a likewiseknown way to accommodate the skeins of a three-phase AC winding (DE 3110 339 C2, DE 33 02 961 C2), substantially consisting of electricalconductors 97 (FIGS. 15 and 16). In order to simplify the assembly andposition-fixing of the conductors 97, walls 98 of the correspondinggrooves 99 in the finished assembly 93 appropriately have a shape whichenables the conductors 97 to be pressed with slight elastic deformationin the direction of the arrows entered into the grooves 99 and thus tofix them without further auxiliary means after the fashion of a snap-inconnection in the assembly 93. For this purpose the walls 98 areappropriately opened downwards by means of slots 100, which at theirnarrowest point have a smaller width than that corresponding to thediameter of the conductors 97. Such a groove shape however generallydoes not correspond to the shape of the grooves 72 of the sheet stack67. These grooves 72 rather have, for electrical and/or magneticreasons, or for reasons relating to the operation of the magneticlevitation track, and in order to achieve a minimal waste during thestamping procedure, the shape visible above all from FIGS. 9 and 10,which is indicated in FIG. 16 by an additional line 101. In order to dojustice to both functions, the tool 75 (FIG. 13) is appropriatelyprovided with a plurality of cores 102 (FIG. 13), which duringpositioning of the sheet stack 67 in the cavity or during closure of thetool, are introduced into the individual grooves 72. The shape of thesecores 102 is selected in accordance with the shape which the finalgrooves 99 should have, so that the walls of the grooves 72 present inthe sheet stack 67, during introduction of the hardenable mixture, areprovided with a comparatively thick lining 103 shown cross-hatched inFIG. 16, which in the finished condition of the assembly 93 lead to thedesired shapes of the walls 98. The remaining applied anti-corrosionlayer on the other hand can be kept relatively thin, as is shown forexample in FIG. 16 by the reference number 104.

[0092] It also applies with respect to the finished assembly 93, that bymeans of introduction of the mixture in one single working step, on theone hand, the sheets 61 are provided with the layers serving for mutualinterconnection, and are connected together forming a finished sheetstack 67, while on the other hand the sheet stack 67 together withfurther components (crosspieces 74) is connected to form a finishedassembly 93 (stator packet). Moreover, when using the method accordingto the invention, the final electrical, magnetic, mechanical and/orgeometric properties of the sheet stacks or assemblies are at leastpartly obtained only by the treatment of all components with the mixturein a tool, particularly if a hardenable mixture with sufficientelectrically insulating properties is used. This applies in particularwith reference to the application of the insulating layers for theindividual plates, the external anti-corrosion means, the permanentconnection of the various parts together and the final external shape ofthe surrounded sheet stacks, assemblies or parts thereof, e.g. grooves99. Of particular advantage in addition is the fact that additionalconnection means such for example as screws, rivets, adhesives or thelike are required neither for positioning nor for connecting theindividual parts, and the mechanical strength and environmentalresistance can be established by the thickness of the externalsurrounding of the mixture.

[0093] As shown in particular by FIG. 12, it may also be appropriate tosupply the sheet stacks or assemblies inserted into the tool at specificpoints, e.g. on their outer sides, with a spacer member 105 consistingof a porous material, e.g. a woven mat produced from plastic fibres orthe like, which holds the sheet stack 67 or the like at a desiredspacing from the walls of the mould hollow. Such elements or mats arefully impregnated with the mixture during the injection procedure, sothat during hardening a stable, strong plastic resin layer results,which forms a mechanically strong external wall on the finished assembly93 and increases its mechanical strength.

[0094] In order to improve the electrical properties (dielectricconstant, loss factor) there may be added to the hardenable mixturessilanes, e.g. the compounds offered by the Company Osi Specialties underthe title Silquest Silane. Suitable silanes are for exampleoctyltriethoxysilane, methyltriethoxysilane and vinyltriethoxysilane.

[0095] In addition, the hardenable mixtures can contain fillers such forexample as metal powder, wood powder, glass powder, glass pearls orsemi-metal and metal oxides. Preferred fillers are Wollastonite, Al₂O₃and SiO₂, quartz powder of the various SiO₂ modifications beingparticularly preferred.

[0096] In addition to the additives mentioned, further additives suchfor example as anti-oxidising agents, light-protective agents,plasticisers, pigments, dye stuffs, thixotropic agents, viscosityimprovers, de-foamers, anti-static agents, lubricants and mould releaseagents can be contained in the hardenable mixtures.

[0097] Moreover, the hardenable mixtures may be produced according toknown methods, conventionally with the aid of known mixing units(stirrers, kneaders, rollers, mills, dry mixers or thin-layer de-gassingmixers). The various methods for producing mixtures are known to theperson skilled in the art and are for example described in Becker/Braun:“Kunstoff-Handbuch, vol. 10, Duroplaste”, Carl Hanser Verlag 1988, pages515 ff and 825 ff.

[0098] It if is desired to stack the individual sheets 1,61 in a wayother than that explained above, they can be fixed with appropriateauxiliary means, e.g. spacers, on the ends in such a way that thespacings between the individual sheets are approximately equal. In thiscase it is irrelevant that the spaces between all the plates are exactlyidentical. There need only be sufficient room for entry of theinsulating resin compound into the inter-spaces between the individualplates 1,61. The spacing between the plates 1 in this way can beadjusted for example from 1 μm to 100 μm, preferably to 2 μm to 5 μm.

[0099] The metal plates usable in the method according to the inventionare preferably steel plates, although other ferromagnetic materials canalso be used.

[0100] The invention is not restricted to the embodiments described,which may be varied in many ways. In particular it is self-evident thatthe magnet poles and stator packets described can be provided also withother components not described in detail, e.g. with electrical ormechanical connections leading outwards, which are likewise fixed and/orformed by the surrounding mixture. Finally, the invention also embracesthe assemblies produced according to the method described, theindividual features also being applicable in combinations other thanthose described and illustrated in the drawing.

1. Method of manufacturing an electromagnetic assembly (45,93) in theform of a magnet pole or stator packet of a long stator linear motor fora magnetic levitation train, this assembly including at least one sheetstack (8,67) consisting of ferromagnetic material, and at least onefurther component (12,13,14,74), characterised in that the sheet stack(8,67) is assembled from raw magnetic steel sheets (1,61), and ispositioned together with the further components (12,13,14,74) ifnecessary using auxiliary positioning means, in a tool (28,75), and inthat then, by introduction of a hardening mixture into the tool (28,75),and hardening or hardening out of the mixture, in one single workingstep the sheets (1,61) are surrounded by the mixture and are connectedtogether to form the finished sheet stack (8,67), the sheet stack (8,67)is connected to the components (12,13,14,74) and the assembly (45,93) inall is provided with its final electrical, magnetic, mechanical and/orgeometric properties.
 2. Method according to claim 1 , characterised inthat the tool (28,75) is at least partly evacuated before introductionof the mixture.
 3. Method according to one of claims 1 or 2,characterised in that it is carried out as a pressure-gelating method.4. Method according to one of claims 1 to 3 , for manufacturing anelectromagnetic assembly (45) in the form of a magnet pole for a longstator linear motor, characterised in that the sheets (1) are providedwith holes (7), and are threaded with these in order to form a sheetstack on rods (9).
 5. Method according to claim 4 , characterised inthat the sheet stack (8), before introduction into the tool (28), isprovided on its end faces with respectively loosely mounted pole jaws(12,13).
 6. Method according to claim 4 or 5 , characterised in that thesheet stack (8) is provided before its introduction into the tool (28)with a loosely applied winding (19).
 7. Method according to one ofclaims 4 to 6 , characterised in that the sheets (1), before formationof the stack of sheets, is provided with apertures (49) intended forproduction of a linear generator, and windings (51) are loosely insertedin the grooves (50) resulting thus after the formation of the sheetstack.
 8. Method according to one of claims 1 to 7 , characterised inthat during introduction of the mixture an underside of the sheet stack(8) and/or of the pole jaws (12,13) are at least partly kept free ofmixture.
 9. Method according to one of claims 1 to 3 for manufacturingan electromagnetic assembly (93) in the form of a stator sheet stack fora long stator linear motor, characterised in that the sheets (61) areprovided on their upper side (63) with apertures (68), which afterassembly of the sheet stack (67) form at least one groove (71), and inthat before introduction of the mixture into the tool (75), a crosspiece(74) serving for assembly of the assembly (93), is inserted into thegroove (71).
 10. Method according to claim 9 , characterised in that thecrosspieces (74) during introduction of the mixture are kept free ofmixture on at least one surface (94).
 11. Method according to claim 9 or10 , characterised in that the sheets (61), before formation of a sheetstack, are provided on their underside (64) with apertures (69), whichafter formation of the sheet stack form at least one groove (72)intended to accommodate an elastically deformable electrical conductor(97), and which has a cross-section selected in dependence on thedesired electromagnetic properties of the sheet stack (67), and in thatthe wall of the groove (72), is provided by the introduction of themixture with a lining (102) consisting thereof, so that a mechanicallyeffective groove (97) results, whose wall (98) has a cross-sectionselected in dependence on the conductor (97).
 12. Method according toclaim 11 , characterised in that the final cross-section is so selectedthat the groove walls (98) are open outwards by means of slots (100),which at their narrowest points have a smaller width than thatcorresponding to the external diameter of the conductors (97). 13.Method according to one of claims 1 to 12 , characterised in that athermally hardenable mixture is used as a hardenable mixture.
 14. Methodaccording to one of claims 1 to 12 , characterised in that, in order toproduce the sheet stack (8,67), raw, non-pre-treated plates are used,and the mutual electrically insulation between the sheets (8,67) isproduced by using a hardenable mixture with electrically insulatingproperties.
 15. Electromagnetic assembly for a magnetic levitation traincharacterised in that it is produced according to the method accordingto one of claims 1 to 14 .